• 2011-05-02

    热舒适讲义03:人如何评价热环境 - [可持续]

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    http://www.blogbus.com/sweetscience-logs/124733684.html

    人如何评价热环境 How does man evaluate the Thermal Environment?

    译者:童梦

    当一个人感觉既不太热,也不太冷时,环境就被认为是舒适的,这种
    情况被称为“热中性”(thermal neutrality)。

    若皮肤温度降低到34℃以下,冷感应器开始向大脑释放刺激信号,人
    体启动御寒机制。感应器释放的信号,会随着温度降低而增加,同时,
    刺激信号也与皮肤温度下降速率有关,下降越快,刺激越强烈。

    同样的,下丘脑中热感应器会在核心体温超过37℃时,释放刺激信号,
    温度越高,刺激信号越多。科学家相信,上述两种体内刺激信号,是
    人类评价热舒适度的基础。

    大脑对冷热信号的反应,在科学假设中,被看成一场拔河比赛,绳子
    的一头是冷刺激,另一头是热刺激,如果两种刺激信号强度一致,人
    体便感觉到热中性,如果强度不一致,人体则感觉到冷或热。处于热
    中性环境中,完全放松的人,是一个特殊情况,他冷热感应器都不活
    动。

    相比皮肤温度而言,核心体温的变化速率要慢,因此,热感应器发出
    的信号,运不如冷刺激信号变化快。

    Man considers the environment comfortable if no type of thermal discomfort is
    present. The first comfort condition is thermal neutrality, which means that a
    person feels neither too warm nor too cold.

    When the skin temperature falls below 34°C, our cold sensors begin to send
    impulses to the brain; and as the temperature continues to fall, the impulses
    increase in number. The number of impulses are also a function of how quickly
    the skin temperature falls - rapid temperature drops result in many impulses
    being sent.

    Similarly, the heat sensor in the hypothalamus sends impulses when the
    temperature exceeds 37°C, and as the temperature increases, the number of
    impulses increase. It is believed that it is the signals from these two sensor
     systems that form the basis for our evaluation of the thermal environment.

    The brain’s interpretation of the signals is assumed to be like a tug-of-war, with
    the cold impulses at one end of the rope and the warm impulses at the other.
    If the signals on both sides are of the same magnitude, you feel thermally neutral,
    if not, you either feel too warm or too cold. A person in a thermally neutral state
    and completely relaxed makes for a special case, as he will activate neither the
    heat or cold sensors.

    It takes some time to change the body’s core temperature; the signal from the
    heat sensor therefore change very slowly compared to the signals from the
    cold sensors.

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